Saturn’s mysterious hexagon explained

There are lots of circles and spheres in the solar system. But there’s only one hexagon.

It’s found on the planet Saturn, and thanks to a spacecraft that’s been orbiting the solar system’s second largest planet for nearly a decade, Cassini, we’ve now got our best look at it.

Saturn’s a big planet, nearly 100 times larger than Earth, by mass. And that awesomely huge hexagon at its north pole is 12,000 miles across.

At the pole itself is a massive hurricane with an eye about 50 times larger than the average hurricane eye on Earth. Both this hurricane and the hexagon itself circulate in a counterclockwise manner.

Further out you can see small vortices that spin clockwise. The biggest one, with a whitish hue, is about 2,200 miles across. You could fit about a dozen Texases in that single vortex. If you’d want to. You might not want that many (maybe an awkward photo of Rick Perry here?).

So what causes this freakishly symmetric hexagon to form?

It’s a jet stream, a narrow current of fast moving gas.

On Earth we have a jet stream, too, which meanders around the north pole in wave-like features called Rossby waves. Changes in the jet stream on Earth have big effects on our weather in the northern Hemisphere. As it turns out observing other planets with jet stream features like the hexagon helps us understand our atmosphere here on Earth, which in turn improves weather forecasting.

So why is our jet stream like a wriggly spaghetti noodle and Saturn’s is not? The jet stream on Saturn is much more tightly defined because the much larger planet spins faster; its day is less than 11 hours long. This confines the jet stream into an absolutely delightful hexagon.

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